Theory of IEC HSBY Operation

Overall PLC Scan The overall scan time for the IEC HSBY supporting PLC type is outlined in the IEC

Time

Scan Time Increase Table below.

 

 

 

 

 

IEC Scan Time Increase

 

 

 

 

 

CPU - HSBY Baseline Configuration

Scantime Increase because of HSBY

 

 

 

 

CPU 434 12 / CPU 534 14

~ 40 ms

 

0x: 1536, 1x: 512, 3x: 512, 4x: 1872

 

 

IEC-HSBY registers (3x): 700

 

PLC to CHS Data

 

 

 

 

Calculating the PLC specific data transfer rate in a Hot Standby system leads to the

Transfer Rate

following result.

 

CPU 434 12 / 534 14

1.9 ms / byte

State RAM

The following table lists the number of bytes required for reference storage

 

 

 

 

Coil (0x)

3 bits

 

 

 

 

Discrete (1x)

3 bits

 

 

 

 

Input Register (3x)

2 bytes

 

 

 

 

Holding Register (4x)

2 bytes plus 2 bits

 

 

 

 

IEC HSBY Register (3x)

2 bytes

 

 

 

 

 

 

840 USE 106 00 January 2003

49

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Image 49
Schneider Electric 840 USE 106 0 manual Time Scan Time Increase Table below, Following result, IEC Scan Time Increase